The present invention concerns a method and apparatus for concentrating isotopes by means of laser radiation having a wave length absorbed only by molecules of a desired isotope mixed with one or more other isotopes, and these molecules, excited thereby, are caused to enter into a chemical reaction with a reaction partner. Such a method has become known, for instance, from the German Auslegeschrift No. 2,296,355. Here, a laser beam of a frequency which corresponds to an absorption frequency of the isotope to be excited, passes through the mixture of isotope molecules and a reaction partner. This selectively excited isotope molecule is thereby enabled to enter into a chemical reaction with a suitable reaction partner, so that essentially only the excited isotope is contained in the reaction product and, thereby, a separation from the mixture or enrichment of the same as to the desired isotope and with respect to the original isotope mixture, is achieved.
Besides these desired reactions, however, also thermally activated reactions occur which are not tied to the molecules of the one isotope excited by the laser radiation, so that the selectivity of the method is degraded thereby. This possibility exists particularly if the activation energy necessary to carry out the chemical reaction, is relatively low.
Since the efficiency of a separation method, however, depends very heavily on its selectivity, the problem arose to find a way to carry out a method of isotope separation of this kind, in which the "thermal competition", i.e., the undesired reactions due to thermal activation, are kept as low as possible.